dolf@idca.tds.philips.nl (Dolf Grunbauer) (08/29/90)
I always assumed that when making a telephone call the line to the otherside is the same the line back from him to me. The other day someone told me that this is not the case, especially when making a international phone call. According to him it is possible that for example when calling from europe to the USA one line could use a satellite connection while the other could use a transatlantic cable. Is this true? Dolf Grunbauer Tel: +31 55 433233 Internet dolf@idca.tds.philips.nl Philips Information Systems UUCP ...!mcsun!philapd!dolf
yazz@ucbvax.berkeley.edu (Bob Yasi) (09/05/90)
Yes, it is true within the US so I see no reason it wouldn't be true elsewhere. I live in San Diego and could NOT get clean connections from AT&T to either New Jersey or Boston. I would sound great to the East Coast but they would sound really bad. I tried for _three months_ to get AT&T to fix the problem, and learned a lot in the process, but they never did fix it. (If the call originated on the East Coast, then both legs would sound fine.) Anyway, that's why I have Sprint now -- AT&T could NOT provide decent service -- which, quite frankly, surprises me to this day. Bob Yazz (no bulky signature, thank-you) --
levin@bbn.com (Joel B. Levin) (09/07/90)
From: Dolf Grunbauer <dolf@idca.tds.philips.nl> >I always assumed that when making a telephone call the line to the >otherside is the same the line back from him to me. The other day >someone told me that this is not the case, especially when making a >international phone call. According to him it is possible that for >example when calling from europe to the USA one line could use a >satellite connection while the other could use a transatlantic cable. >Is this true? It could be worse. A number of years ago (I think it was summer of '84, when the Bell breakup was to have taken place but effects were not everywhere felt) I was in San Francisco installing a packet switch for a commercial client. We were trying to obtain a leased line to New York, and while waiting for it to be installed we were attempting to use dial-ups and modems. Rather to our horror we learned from AT&T that of cross country dial-up calls like those, no more than 10% - 15% were terrestrial both ways. Terrestrial capacity was scarce compared to satellite service. People notice (and complain about) delays and echo problems on two-way satellite calls such as are common on intercontinental phone calls, but if one direction was terrestrial the effect was generally not noticed by the speakers, so most calls were satellite one way. The scary part was that AT&T said that a few months later they would no longer guarantee two-way terrestrial service for leased lines (at least 9.6kb lines). When you are doing store-and-forward packet switching this can have a major effect on things like buffer management or line utilization, especially if you don't know about the satellite delay. I don't know if they ever carried out that policy change. We mostly used higher speed lines in our other business, and we would definitely have noticed it there. JBL